Make ParameterBuilder abstract

[buyaa-n]

With Abstract System.Reflection.Emit public types we have abstracted other System.Reflection.Emit.XyzBuilder types, ParameterBuilder type left out from this effort (probably because it lives in different ref file).

The type also needs to be abstracted same as others because:

• Because of internal constructor could not create an instance of it outside of CoreLib. (The new AsemblyBuilder implementation will be added outside of CoreLib)
• Even if we workaround the internal constructor we could not get CustomAttributes info set to the ParameterBuilder instance, same for the default value.

Suggested API change:

namespace System.Reflection.Emit
{
-   public class ParameterBuilder
+   public abstract class ParameterBuilder
    {
-       internal ParameterBuilder() { }
+       protected ParameterBuilder() { }
        public virtual int Attributes { get { throw null; } }
        public bool IsIn { get { throw null; } }
        public bool IsOptional { get { throw null; } }
        public bool IsOut { get { throw null; } }
        public virtual string? Name { get { throw null; } }
        public virtual int Position { get { throw null; } }
        public virtual void SetConstant(object? defaultValue) { }
        public void SetCustomAttribute(ConstructorInfo con, byte[] binaryAttribute) { }
+       protected abstract void SetCustomAttributeCore(ConstructorInfo con, byte[] binaryAttribute);
        public void SetCustomAttribute(CustomAttributeBuilder customBuilder) { }
    }
}

Tagging subscribers to this area: @dotnet/area-system-reflection
See info in area-owners.md if you want to be subscribed.

Issue Details

---

With Abstract System.Reflection.Emit public types we have abstracted other System.Reflection.Emit.XyzBuilder types, ParameterBuilder type left out from this effort (probably because it lives in different ref file).

The type also needs to be abstracted same as others because:

• Because of internal constructor could not create an instance of it outside of CoreLib. (The new AsemblyBuilder implementation will be added outside of CoreLib)
• Even if we workaround the internal constructor we could not get CustomAttributes info set to the ParameterBuilder instance, same for the default value.

Suggested API change:

namespace System.Reflection.Emit
{
-   public class ParameterBuilder
+   public abstract class ParameterBuilder
    {
-       internal ParameterBuilder() { }
+       protected ParameterBuilder() { }
        public virtual int Attributes { get { throw null; } }
        public bool IsIn { get { throw null; } }
        public bool IsOptional { get { throw null; } }
        public bool IsOut { get { throw null; } }
        public virtual string? Name { get { throw null; } }
        public virtual int Position { get { throw null; } }
        public virtual void SetConstant(object? defaultValue) { }
        public void SetCustomAttribute(ConstructorInfo con, byte[] binaryAttribute) { }
+       protected abstract void SetCustomAttributeCore(ConstructorInfo con, byte[] binaryAttribute);
        public void SetCustomAttribute(CustomAttributeBuilder customBuilder) { }
    }
}

Author:	buyaa-n
Assignees:	-
Labels:	api-suggestion, area-System.Reflection, untriaged
Milestone:	-

[teo-tsirpanis]

How about we seize the opportunity and make SetCustomAttributeCore accept a ReadOnlySpan<byte>? No need to also expose it as a public method, this can happen as part of #63419.

[buyaa-n]

Internal implementation currently works with byte[], of course we could refactor that, I think that is better handled by #63419 with all other types custom attributes handling (looks all of them handled similarly).

[terrajobst]

Video

• The core method should be based on ReadOnlySpan<byte>
  • We should align the other ones we added this release

namespace System.Reflection.Emit;

-public class ParameterBuilder
+public abstract class ParameterBuilder
 {
-    internal ParameterBuilder();
+    protected ParameterBuilder();
     public virtual int Attributes { get; }
     public bool IsIn { get; }
     public bool IsOptional { get; }
     public bool IsOut { get; }
     public virtual string? Name { get; }
     public virtual int Position { get; }
     public virtual void SetConstant(object? defaultValue);
     public void SetCustomAttribute(ConstructorInfo con, byte[] binaryAttribute);
+    protected abstract void SetCustomAttributeCore(ConstructorInfo con, ReadOnlySpan<byte> binaryAttribute);
     public void SetCustomAttribute(CustomAttributeBuilder customBuilder);
 }